Extract amplitude and latency for P1, N1, P2, P3

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1

Hi

Could you advise how I can extract the amplitude and latency values for these components (P1, N1, P2, P3) from my EEG data? I have tried the "extract>find maximum in time" process at -100.1 to 500 ms. I exported to Excel where I got a value for both -100.1 and 500 ms.

Thanks
David

2

This process "Extract>Find maximum in time" saves either the latency OR the amplitude at the peak, for each signal selected in input. In both cases, it saves the result in a "data" file.
To be able to open and display this file, we need to set two time points, therefore the value that is extracted (amplitude or latency) is duplicated. The time vector of this file is set to be the input time.

What you see in your Excel file doesn't mean that there are two values (one for -100ms and one for 500ms), but that this one duplicated value was found in the interval [-100ms,500ms].
If you want both the latency and the peak amplitude, you need to run the same process twice with different options.

3

Thank you Francois

4

Hi Francois,

I am trying to extract the amplitude for some component, e.g. P50 in the way: extract values (average selected time window), time window - 40 - 80 ms, but the extracted value is too small (e.g., 5.388837780212412e-06). It seems like the Brainstorm extracted the value in Volts but not microVolts. Is it possible to extract the microvolts?

Thank you!

5

I think actually that's what you're looking for: 5.38 μV

1 Like
6

Indeed, Brainstorm stores all its data in international units: Volts, Ampers, meters.
This is much simpler than having to store the unit modifiers for every value.

7

Thank you!